Textile fire retardant treatment



2,828,228 Tnxrnn Finn RETARDANT TREATMENT Nathaniel .l'. Glade and lngenuin Hechenhleikner, Stainford, and Donald W. Kaiser, Old Greenwich, Conn, assignors to American (Iyanamid (Iompany, New York, N Y., a corporation of Maine No Drawing. Application January 12, 1954 Serial No. 403,651

24 Claims. (Cl, 117-136) The present invention relates to a wash-durable fire retardant treatment for cellulosic textiles.

Although numerous fire retardant treatments have been applied to textile fabrics with varying degrees of success, the great majority of these finishes are either removed or rendered inefiective upon laundering the treated fabric, especially when an alkaline wash is employed. Cloth treated with these non-durable agents must be reprocessed after washing in order to render the fabric flame retardant again. Many treatments are complicated by the necessity for using two treating baths. In addition, obnoxious or highly poisonous gases are released during the curing stage of the application of some fire retardant finishes to textiles with attendant discomfort or danger to the personnel of the finishing plant. Accordingly, there is a widespread demand for an effective fire retardant agent for cellulosic textile fabrics which is both durable to severe alkaline washes and which may be applied to the fabric without discomfort or the need for special safety precautions.

An object of the invention is to provide an improved fire retardant finish for cellulosic material which is durable to repeated laundering.

Another object of the invention is to provide an improved method of applying a wash-durable fire retardant composition to cellulosic textile fabrics by means of a single aqueous bath.

Other objects and advantages of the invention will be apparent to those skilled in the art upon consideration of the detailed disclosure hereinbelow.

The present invention relates to a mixture of a methylol melamine with an aliphatic amidophosphate containing from 1 to 6 carbon atoms and having the structural formula:

X \NHRZ wherein R is an alkyl, alkoxyalkyl or halogenated alkyl radical having from 1 to 4 carbon atoms, R is hydrogen or an alkyl radical having from 1 to 4 carbon atoms, and X is O.R or NHR Other aspects of the invention relate to a process of applying a solution of this mixture to cellulosic material with heating of the treated material in the presence of a curing catalyst and in the resulting article having the heatcured reaction product as a wash-durable fire retardant finish.

Among the suitable resin-forming compounds operative in this invention are the water-soluble or water-dispersible methylol melamines which term is used herein to include not only condensates of melamine and formaldehyde such as dimethylol melamine, trimethylol melamine up to hexamethylol melamine per se but also alkylated methylol melamines which are produced by condensing 2,828,228 Patented Mar. 25, 1958 the methylol melamines with a lower alcohol such as methanol, ethanol, etc. These alkylated methylol melamines are believed to include 2,4-dimethoxymethyl 6- methylol melamine, 2,4-dimethoxymethyl melamine, 2- methylol 4,6-diethoxy methylol melamine, 2,4-dimethylol 6-methoxymethyl melamine, and Z-methylol 4-methoxymethyl o-ethoxymethyl melamine, 2-ethoxymethy1 4,6 methylol melamine and 2,4,6 trimethoxymethyl melamine, to name only a few. It will be appreciated by those skilled in the art that these compounds are probably always present as mixtures. For example, one of the preferred resin-forming materials is amorphous dimethylol melamine which is prepared by condensing 2 mols of formaldehyde or an equivalent amount of a formaldehyde engendering substance per mol of melamine to produce principally dimethylol melamine in admixture with some monomethylol melamine, some trimethylol melamine and perhaps some higher polymethylol melamines. Similarly when a mol of methylol melamine is alkylated with 1, 2 or 3 mols of an alcohol, the product is probably a mixture of mono-, di-, and trialkylated methylol melamines even though the degree of alkylation of methylol radicals is about two-thirds for example. Such a product, which may be termed dimethylated trimethylol melamine, has been outstanding for the present purposes. In general, resin-forming melamine compounds containing at least two active methylol or alkylated methylol groups are suitable. While essentially monomeric, it is possible that there is some dimerization of the aforesaid melamine compounds during preparation. The preparation of such compounds is well known to those skilled in the art and need not be detailed here. It is also contemplated that the melamine compound may be present in the acid colloid form wherein the melamine resin is colloidally soluble or dispersible in water as a partially polymerized cationic material rather than the substantially monomeric substances described above. Such colloids may be prepared with either phosphoric acid or a weak organic acid such as formic acid, acetic acid, etc. in the manner disclosed in Wohnsiedler et a1. Patent No. 2,345,543.

The lower aliphatic amidophosphates useful in the present invention are set forth in the general formula above. They may be dialkyl amidophosphates, monoalkyl diamidophosphates, or the designated substituted alkyl and substituted amide compounds used either alone or in admixture. To retain the desired water-solubility, these substances should contain from 1 to 6 carbon atoms per molecule, and the alkyl group attached to the oxygen atom or replacing one of the hydrogen atoms of an amide group should not exceed 4 carbon atoms. In addition, the organic radical attached to the oxygen atom or atoms may be a halogenated alkyl or an alkoxyalkyl radical containing up to 4 carbon atoms. Suitable compounds include, inter alia, dimethyl amidophosphate, diethyl amidophosphate, di-n-propyl amidophosphate, methyl ethyl amidophosphate, methyl isopropyl amidophosphate, ethyl propyl amidophosphate, primary, secondary and isobutyl ethylamidophosphates, methyl bromoethyl amidophosphate, chloroethyl bromobutyl amidophosphate, dimethyl N-ethylamidophosphate, diethyl N- butylamidophosphate, di-Z-bromoethyl N-isopropyl amidophosphate and the like as monoamides and 2-methoxyethyl diamidophosphate, methyl bis(methylamido)-phosphate, methyl N-secbutyldiamidophosphate, methyl N. ethyl N isopropyldiamidophosphate, ethyl bis(ethylamido)phosphate, 2-chloroethyl N-mcthyl-N'-propyldiamidophosphate, isopropyl N-methyl-N-ethyldiamidophosphate, n-butyl bis(rnethylamido)-phosphate, isobutyl N-ethyldiamidophosphate, and the like as diamides as well as mixtures of the foregoing compounds.

The phosphate compounds mentioned above may be prepared in the manner described and claimed in the concurrently filed application Serial No. 403,652 of Hechen' bleiltner or according to the methods described in the concurrently filed application Serial No. 403,653 of Kaiser ct al. which describes and claims aliphatic diamidophosphates. The products of those preparatory rnods commonly contain a sufficicnt amount of ammonium chloride and ammonium phosphate salts to some catalysts for curing the resin-containing mixtures.

lt is desirable in some instances to prepare an alphatic amidophosphatc which is substantially free of these am monium salts in order that this material may be m" with a melamine resin and sold as a combination h a long shelf life without precipitation as a concentrated or dilute aqueous solution. Such a combination reduces the formulating problems of the textile finisher. A relatively pure dialkyl amidophosphate may be obtained by preparing and purifying the corresponding dialkyl hydro gen phosphite; then introducing either ammonia or the selected lower alkylamine until the mixture is saturated while maintaining the reaction temperature at approximately C. in the presence of a carbon tetrachloridechloroforrn mixture as the inert reaction solvent. After filtering out the ammonium chloride and evaporating the solvent, a crystalline mass is obtained which may be purified by recrystallization from aeetonitrilc, chloroform or other suitable solvent. However, it is contemplated that no srrch purified phosphate compound will be rcquired for many applications because the melamine resin and the phosphate may be added separately to a pad bath at the textile finishing plant and the presence of residual ammonium salts in the alkyl amidophosphate obviates the need for an additional curing catalyst.

The present invention is particularly directed at the treatment of materials containing cellulose, especially those of fibrous nature. In the textile field this includes those containing cotton, linen, viscose rayon. cnprammonium rayon, jute, hemp and ramie.

The treated fabrics have shown not only outstanding llame retardant qualities initially and after repeated harsh laundering but also an excellent retention of tensile strength. In fact the loss in tensile strength is negligible where alkyl diamidophosphate-resin mixtures have been applied. Moreover. very good resistance to shrinkage, wrinkling and mildew are also obtained. Thus the treated materials of the present invention are capable of a wide variety of uses both indoors and outdoors by reason of their exceptional durability to rain and other weather conditions as well as to the aforementioned desirable qualities. They may be employed as tarpaulins, tents, boat covers, awnings, stage scenery, upholstery fabrics, slip covers, draperies, batting, insulation, padding, rope, string, twine and wearing apparel for welders, foundrymen, military personnel and the like as well as fabrics for covering the wings and fuselages of airplanes. In the textile industry, any material of appreciable cellu losic fiber content including raw fiber, carded stock, r vings, threads, yarns, felts may be treated as well as the knitted and woven fabrics which appear to provide the largest field of utility.

The process of the present invention may be carried out in any manner which insures that the fabric is impregnated or coated with an aqueous solution of the phosphate compound and melamine resin by spraying, immersing or roll application in such manner as to deposit sufficient quantities of the treating agent on the fabric followed by heating the material in the presence of a curing catalyst or accelerator for a sufficient time to convert the treating agent to a substantially water-insoluble state. Excellent results are obtainable with a conventional padder followed by drying and curing with equipment operating at a temperature ranging from 200 to 500 F. for a time range ranging from 10 seconds to 30 minutes and decreasing with increasing tcmpertrure. in general, it is recommended that the fabric be dried and cured with equipment operating at between 250 and 375 F. for a period of from 1 to 10 minutes.

The concentration of active components in the treating bath or baths and the wet pick-up may be varied considerably provided that a sulficient amount of the watersoluble mixture is deposited on the cellulosic material to provide substantial wash-durable flame retardance. These baths are slightry acid with a pH usually between 3.5 to 6.8 and perdorninantly in the upper part of this range for non-colloidal melamine resins and somewhat lower for the resin acid colloids. In general at least about 4% of the alltyl amidophosphate based on the dry weight of the untreated material is necessary and 7 to 20% is preferred. The melamine resin pick-up should be from one-half to three or more times the weight of the phosphate compound; howcver, even for mild or home laundering the methylol melamine deposited should amount to at least 5% of the dry untreated material weight and quantities of about 8 to l5% are preferred for durability of the finish to severe washing. If desired the combination composition may be applied in far larger amounts, such as 50 to solids on a treated material where stiffness is not objectionable; however the optimum for many purposes appears to be about i095 of the amide compound and 15% of the resin-forming component. For simplicity all of the quantities mentioned here are set forth in regard to substantially pu'e compounds on the material in the wet state prior to curing. Actually the alltyl amidophos phates used in the examples below with one exception contained from about 1 to about 30% of other substances which are believed to comprise ammonium chloride, trialltyl phosphates and ammonium salts of phosphoric and substituted phosphoric acids. Most or all of these compounds are thought to be removed by volatilization during curing or by subsequent rinsing or washing. The melamine resin also loses weight during curing by splitting off water, formaldehyde and/or alcohol. Thus the dry add-on of the finished fabric is considerably smaller than the wet pick-up of solids from the treating bath. In the finished article it appears desirable to have a deposit of about 0.5 to 2.0 or more percent phosphorus based on the dry untreated cellulosie material and an amount of melamine resin wihin the limits set forth above.

In order to achieve the curing speed required in commercial finishing operations, it is essential that the compositions disclosed herein be cured in the presence of a curing catalyst or accelerator which is capable of curing a melamine resin to the water-insoluble state. Although this catalyst can be applied to the wet impregnated web of fabric by spraying the catalyst onto the web immediately prior to the eurins operation, it is usually desirable to have the curing catalyst included in the treating bath in order to obtain the advantages of a single bath operation, as is possible here. Any catalyst suitable for curing melamine resins on cellulosic materials may be used as, for example, oxalic, tartaric and other acids, particularly the mild organic acids, ammonium chloride, ammonium sulfate, ammonium phosphates especially diammoniurn hydrogen phosphate, ammonium diethyl phosphate, magnesium chloride, acid salts of organic amines such as isopropanolamine hydrochloride and various known butanolamine hydrochlorides and the like. Unless the alkyl amidophosphate has been purified the ammonium salts therein will usually be sufiicient to catalyze curing without adding further accelerating agents. The required amount of curing agent varies somewhat with the particular catalyst already present or selected, but in general a tota. at least about 0.5% and preferably at least about 2.0% based on the dry weight of resin-forming solids should be included in the composition; however, quanti ties up to 30% or even more may be used if desired.

The chemistry of the present invention is not fully understood. The fiame retardant effect of the present compositions is not predictable from the materials used. For instance, a cotton poplin impregnated with a 15% aqueous solution of dimethylated methylol melamine to an estimated wet pick-up of 85% followed by drying and curing in the manner indicated in Example IV hereinbelow burns completely upon application of the standard A. A. T. C. C. vertical flame test. Also a sample of the same material also burns completely in this test after impregnation to 85% Wet pick-up with diethyl amidophosphate alone in a 15% aqueous solution followed by drying without rinsing or washing; yet excellent fireproofing is obtained by the treatment with a solution containing 15% of this resin and 15% of this amidophosphate as set forth in connection with Example IV. Upon similarly applying a 15 solution of dimethyl amidophosphate alone to the poplin, very mediocre flame resistance is obtained. From the outstanding durability of the finish to many hours of severe alkaline washing, in some instances more than 25 hours, there is reason to believe that the organic phosphate compound is bound to the cellulosic material by a chemical rather than mechanical bonding. Accordingly, it may be postulated that the alkyl amidophosphate is linked to the melamine resin which in turn is linked to a reactive group such as a hydroxyl group on the cellulose. This theory is mentioned merely as a possible explanation of the results obtainable with the present invention and it is to be understood that the invention is not limited to this theory.

It has been found that dimethyl amidothiophosphate in which a single sulfur atom is attached to the phosphorus through a double bond in combination with a melamine resin of the type described will achieve some of the benefits, although to a lesser extent, than the compositions of the present invention; however, objectionable odors are released during the curing operation. A cellulosic fabric treated in this manner has a lower degree of fire retardance and the finish is considerably less durable to repeated laundering operations. The treated fabric has no odor, but, a very powerful and penetrating odor, probably due to the formation of mercaptans, is given off when the thiophosphate-treated fabric is exposed to a flame. This serves as an excellent warning of an undetected fire or smoldering of the treated cloth inasmuch as the odor is far more readily noticeable than the usual smoke odor from a burning fabric.

For a better understanding of the nature and objects of this invention reference should be had to the accompanying illustrative examples which are not intended to be of a limiting nature, and wherein all quantities are given in terms of weight unless otherwise specified.

EXAMPLE A An untreated 5.5 oz. white mercerized cotton poplin is subjected to certain of the tests listed in Table I below for comparative purposes. This material burns completely when subjected to the standard A. A. T. C. C. vertical flame test.

Example 1 The same cotton poplin used in Example A is padded through an aqueous solution of 15% by weight of butyl diamidophosphate containing about one-tenth of ammonium salts and 15% of dimethylated trimethylol melamine in a laboratory Microset Padder. The cloth is passed through 2 dips and 2 nips at 15 lbs. pressure to produce a wet pick-up of approximately 85% of the dry Weight of the fabric. The treated fabric is dried and cured in a single operation at 290 F. for 6 minutes in a circulating hot air oven. Next, the cured fabric is subjected to 2 separate S-minute rinses in water at 160 'F. in a Nojart reversing wash wheel and subsequently dried at 200 F. for 10 minutes. Thereafter, various samples of the treated cloth are subjected to 5 sequential onehour Wash cycles in the Nojart washer. Each cycle consists of washing for 45 minutes in an aqueous solution of 0.1% soap and 0.1% sodium carbonate at F., then rinsing twice for first 5 and then 10 minutes at 160 F. with fresh water and drying while relaxed for 10 minutes at 200 F. in a circulating hot air oven. The total tensilo strength is determined by the Suter method by adding the sum of the tensile strength in the warp direction and the tensile strength in the fill direction. Crease resistance is determined according to the roller pressure method in both directions. The observed values are listed in Table I below.

Example 2 The procedure of Example 1 is repeated substituting l5% ethyl diamidophosphate for the butyl compound. The results observed are tabulated in Table I below.

Example 3 Example 1 is repeated with 15% dimethyl amidophosphate substituted for the butyl compound. Again the results are tabulated in Table I below.

Example 4 The procedure of Example 1 is again repeated using 15% diethyl amidophosphate in lieu of the butyl diamidophosphate to treat the same fabric. The test results obtained with this treated fabric are set forth in Table I below.

TABLE I Example A 1 2 3 4 Bath pH 6. 4 5. 3 6. 1 Total Tensile Strength, lbs 154 155 151 139 126 Total Crease Resistance, degrees... 200 235 232 Shrinkage, Percent:

1 Hr. Wash 8. 9 2. 5 l. 4 1. 7 3 Hr. Wash 10. 3 3. 3 2. 2 2. 2 5 Hr. Wash 11.4 3. 9 2. 8 2. 5 Flammability Char Length,

inches:

After Cure 2.8 2.8 3. 2 3.0 2 Rinses 3.0 3. 2 3. 5 3. 5 1 Hr. Wash 2. 7 3. 2 3.0 3 Hr. Wash 3. 2 3. 4 3. 5 5 Hr. Wash. 3.1 3. 4 3. 9 3. 4 Afterflarning None None None None Afterglow None None None None Percent Finish on Cloth:

After 2 Rinses 15. 6 l5. 2 17.0 5 Hr. Wash 15. 1 12.5 14. 9 Percent N on Cloth:

After 2 Rinses 4. 7 4. 23 4. 36 5 Hr. Wash 3. 90 4. 06 4. 29 Percent P on Cloth:

After 2 Rinses 1.20 .88 .85 5 Hr. Wash 1.02 0.68 0.80

EXAMPLE B Example A is repeated with the same fabric for twenty one-hour wash cycles of the type desecribed in Example 1.

Example 5 Example 4 is repeated using the same 5.5 oz. poplin and continuing the washing tests for 20 hours with the treated fabric being rinsed and dried in each wash cycle.

EXAMPLE C Example A is repeated using an 8.5 02. Navy herringbone cotton twill in place of the poplin and continuing the wash tests for a period of 25 hours. This untreated material also burns completely in the vertical flame test.

Example 6 Example 4 is repeated using the 8.5 oz. H. B. twill and continuing the washing tests for 25 hours.

Flammability Char Length, Inches:

After 2 Rinses 1 Hr. Wash 5 Hr. \VaslL"- 1 Hr. Wash;

5 Hr. Wash 140 117 221 192 Hr. Wash- 135 114 223 189 Hr. Wash 136 108 Hr. Wash 133 103 229 196 Hr. Wash 231 190 Example 7 Another piece of the 5.5 oz. cotton poplin is impregnated in a treating bath of 15% diethyl amidophosphate containing about one-tenth of ammonium salts and 15% by weight of amorphous dimethylol melamine according to the procedure of Example 1. The vertical char length is found to be 2.4 after curing the resinous mixture on the fabric, 2.9" after the two rinses, 3.1" after a one-hour wash cycle, and 3.0" after 3 one-hour wash cycles. At no time is afterflaming or afterglow observed. The fabric after the curing and rinsing operations is found to have a total tensile strength of 142 lbs. in contrast to 145 lbs. for untreated fabric.

Example 8 The procedure of Example 1 is repeated using a weaker impregnating bath containing 10% diethyl amidophosphate and 10% of dimethylated trimethylol melamine and the corresponding amount of ammonium salts as a curing catalyst. In the flammability test the vertical char length is found to be 3.7 after curing the fabric, 3.8" after the two rinses, 4.3" after one wash cycle, 5.1 after three wash cycles and 4.7 after five wash cycles of the nature described. As in the preceding examples, no afterflanr ing or afterglow is observed in these flammability tests. The Suter tensile strength is determined to be 123 lbs. in comparison with 152 lbs. for the untreated fabric, and the crease resistance by the roller pressure method is 223 in contrast with 161 for the untreated material.

Example 9 Another sample of the 5.5 oz. cotton poplin is treated according to the procedure of Example 1 using a bath containing 15% by weight of di-isopropyl amidophosphate and 15% of dimethylated trimethylol melamine along with 3.5% of a curing catalyst consisting of 94 parts of diammonium hydrogen phosphate and 6 parts of hexamethylene tetramine by weight. This particular amidophosphatc is of such high purity that an accelerator is necessary to cure the resin. After curing and rinsing the vertical char length is found to be 4.2" and after 5 one-hour wash cycles the char length is 5.9 without afterflaming or afterglow.

Example 10 The procedure of Example 1 is repeated with an aqueous bath of 15% beta-chloroethyl diamidophosphate containing about one-tenth of ammonium salts and 15% of dimethylated trimethylol melamine. The vertical char length of the treated fabric after rinsing is 2.8 and this increases to 3.5" after 5 hours of the alkaline washing described; again, the absence of afterflaming and afterglow is noted.

Example 1] The procedure of Example 1 is substantially duplicated using a treating bath of 15 isobutyl diamidophosphate containing ammonium salts and 15 of weight of dimethylated trimethylol melamine. After curing and rinsing the cotton poplin, the tensile strength is found to be excellent and the vertical char length amounts to 3.7". After 5 hours of the washing described the char length is found to be 4.9 with no aftcrflaming or afterglow.

Example 12 Again repeating the procedure of Example 1 with the substitution of 15% propyl diamidophosphate for the butyl compound, before washing, the treated fabric is observed to have a. vertical char length of 3.3" in the standard flammability tests and a value of 3.8" is obtained after 5 hours of wash cycles with no afterfiaming or afterglow in either case.

Example 15' The procedure of Example 1 is repeated except that the bath contains 15% of methyl diamidophosphate having an ammonium salt content of approximately onetenth and 15% of dimethylated trimethylol melamine. Again the cotton poplin displays excellent durability to alkaline washing for five hours with a vertical char length of 3.4 before washing and 3.7 after washing and no after-flaming or afterglow.

Example 14 A piece of 5 oz. viscous rayon gabardine is treated according to the process of Example 4 and found to have excellent flame retardance which is substantially retained after repeated wash cycles of the nature described. The untreated material burns completely upon application of a flame.

We claim:

1. A composition of matter which comprises a watersoluble mixture of a methylol melamine with an aliphatic amidophosphate containing from one to six carbon atoms and having the structural formula:

a P X/ \NHB2 wherein R is a radical of the group consisting of alkyl, alkoxyalkyl and halogenated alltyl radicals having from 1 to 4 carbon atoms, R is of the group consisting of hydrogen and alkyl radicals having from 1 to 4 carbon atoms, and X is a radical of the group consisting of -OR and -NHR radicals.

2. A composition of matter which comprises a watersoluble mixture of a methylol melamine with an alkyl amidophosphate containing from one to six carbon atoms and having the structural formula:

P 11 0 \NH:

wherein each R represents an alkyl radical containing from one to four carbon atoms.

3. A composition of mattter which comprises a Watersoluble mixture of a methylol melamine with an alkyl amidophosphate containing from one to six carbon atoms and having the structural formula:

wherein R is an alkyl radical containing from one to four carbon atoms.

4. A composition of matter which comprises a watersoluble mixture of a methylated methylol melamine with diethyl amidophosphate.

5. A composition of matter which comprises a watersoluble mixture of a methylated methylol melamine with dimethyl amidophosphate.

6. A composition of matter which comprises a watersoluble mixture of a methylated methylol melamine with buytl diamidophosphate.

7. A composition of matter which comprises a watersoluble mixture of a methylated methylol melamine with ethyl diamidophosphate.

8. A composition of matter which comprises a watersoluble mixture of a methylated methylol melamine with beta-chloroethyl diamidophosphate.

9. An article which comprises a cellulosic material having as a wash-durable fire retardant finish the heat-cured reaction product of the composition of claim 1.

10. An article which comprises a cellulosic material having as a wash-durable fire retardant finish the heatcured reaction product of a composition according to claim 2.

11. An article which comprises a cellulosic material which having as a wash-durable fire retardant finish the heat-cured reaction product of a composition according to claim 3.

12. An article which comprises a cellulosic textile fabric having as a wash-durable fire retardant finish the heat-cured reaction product of a composition according to claim 4.

13. An article which comprises a cellulosic textile fabric having as a wash-durable fire retardant finish the heat cured reaction product of a composition according to claim 5.

14. An article which comprises a cellulosic textile fabric having as a wash-durable fire retardant finish the heat-cured reaction product of a composition according to claim 6.

15. An article which comprises a cellulosic textile fabric having as a wash-durable fire retardant finish the heat-cured reaction product of a composition according to claim 7.

16. An article which comprises a cellulosic textile fabric having as a wash-durable fire retardant finish the heat-cured reaction product of a composition according to claim 8.

17. A process which comprises treating a cellulosic material with a solution containing the composition of claim 1 and heating the treated material in the presence of a curing catalyst whereby a wash-durable fire retardant finish is imparted to the cellulosic material.

18. A process which comprises treating a cellulosic material with a solution of the composition of claim 2 and heating the treated fabric in the presence of a curing catalyst to impart a wash-durable fire retardant finish to the material.

19. A process which comprises treating a cellulosic material with a solution of a composition according to claim 3 and heating the treated fabric in the presence of a curing catalyst to impart a wash-durable fire retardant finish to the material.

20. A process which comprises treating a cellulosic textile fabric with an aqueous solution of a composition according to claim 4 and heating the treated fabric in the presence of a curing catalyst to impart a wash-durable fire retardant finish to the textile fabric.

21. "A process which comprises treating a cellulosic textile fabric with an aqueous solution of a composition according to claim 5 and heating the treated fabric in the presence of a curing catalyst to impart a Wash-durable fire retardant finish to the textile fabric.

22. A process which comprises treating a cellulosic textile fabric with an aqueous solution of a composition according to claim 6 and heating the treated fabric in the presence of a curing catalyst to impart a wash-durable fire retardant finish to the textile fabric.

23. A process which comprises treating a cellulosic textile fabric with an aqueous solution of a composition according to claim 7 and heating the treated fabric in the presence of a curing catalyst to impart a wash-durable fire retardant finish to the textile fabric.

24. A process which comprises treating a cellulosic textile fabric with an aqueous solution of a composition according to claim 8 and heating the treated fabric in the presence of a curing catalyst to impart a washdurable fire retardant finish to the textile fabric.

References Cited in the file of this patent UNITED STATES PATENTS 2,574,516 Walter et a1. Nov. 13, 1951 2,596,937 Nielsen et al May 13, 1952 2,666,778 Steinberg Ian. 19, 1954 2,668,096 Reeves et al. Feb. 2, 1954 UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,828,228 March 25, 1958 Nathaniel J. Glade et a1.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 13, for perdominantly read -predominant1y-; line 47, for wihin read within-; column 8, claim 2, the formula should appear as shown below instead of as in the patent- RO/ NHa column 9, line 17, strike out which.

Signed and sealed. this 24th day of June 1958.

KARL H. AXLINE, ROBERT C. WATSON, Attesti-ng Ofiicer. Gammz'ssioner of Patents. 

1. A COMPOSITION OF MATTER WHICH COMPRISES A WATERSOLUBLE MIXTURE OF A METHYLOL MELAMINE WITH A ALIPHATIC AMIDOPHOSPHATE CONTAINING FROM ONE TO SIX CARBON ATOMS AND HAVING THE STRUCTURAL FORMULA: 